Professor Alan Barrett:

I have worked on a study in this area. I have to confess it was ten or 12 years ago. I am not aware of any dramatic change in the fundamental patterns in the interim. At the time, we had data on whether people had taken time out of the labour market and, if so, how much time they had actually taken out. If one has that sort of data and one can do the calculations, one can then make the estimate to which I have referred, at which point practically all the wage gap disappears.